Tk_CreateClientMessageHandler(3) Tk Library Procedures

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NAME

Tk_CreateClientMessageHandler, Tk_DeleteClientMessageHandler -
associate procedure callback with ClientMessage type X events

SYNOPSIS

#include <tk.h>

Tk_CreateClientMessageHandler(proc)

Tk_DeleteClientMessageHandler(proc)

ARGUMENTS

Tk_ClientMessageProc *proc (in) Procedure to invoke
whenever a ClientMessage X
event occurs on any
display.
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DESCRIPTION

Tk_CreateClientMessageHandler arranges for proc to be invoked in the
future whenever a ClientMessage X event occurs that is not handled by
WM_PROTOCOL. Tk_CreateClientMessageHandler is intended for use by
applications which need to watch X ClientMessage events, such as drag
and drop applications.

The callback to proc will be made by Tk_HandleEvent; this mechanism
only works in programs that dispatch events through Tk_HandleEvent
(or through other Tk procedures that call Tk_HandleEvent, such as
Tcl_DoOneEvent or Tk_MainLoop).

Proc should have arguments and result that match the type
Tk_ClientMessageProc:
typedef int Tk_ClientMessageProc(
Tk_Window tkwin,
XEvent *eventPtr);
The tkwin parameter to proc is the Tk window which is associated with
this event. EventPtr is a pointer to the X event.

Whenever an X ClientMessage event is processed by Tk_HandleEvent, the
proc is called if it was not handled as a WM_PROTOCOL. The return
value from proc is normally 0. A non-zero return value indicates
that the event is not to be handled further; that is, proc has done
all processing that is to be allowed for the event.

If there are multiple ClientMessage event handlers, each one is
called for each event, in the order in which they were established.

Tk_DeleteClientMessageHandler may be called to delete a previously-
created ClientMessage event handler: it deletes each handler it finds
that matches the proc argument. If no such handler exists, then
Tk_DeleteClientMessageHandler returns without doing anything.
Although Tk supports it, it's probably a bad idea to have more than
one callback with the same proc argument.

KEYWORDS

bind, callback, event, handler

Tk 8.4 Tk_CreateClientMessageHandler(3)